Northern Sharks

Finally

151 posts in this topic

It seems, where I left off, that the morphotype of the species M. nolfi has been highly contested because of incomplete or very similar dentitions to those of other species. I knew the relationship that was made with I. affinis, Mr. praecursor, and also M. americanus, and I knew that Mr. nolfi has been found in the London clay and Kazakhstan. Zhelezko and Koslov have also redescribed in 1999, M. nolfi for M. americana-like teeth with more defined cusplets from the Ypresian of Kazakhstan, and have also included included M. americana in the Bartonian of Kazakhstan.

But I did not knew that M. nolfi was the current nomenclature for I. schoutedeni, what you seem to suggest.

I have not yet found sufficient documents and I try to understand the current kinship ties that have been established, and I wonder what to think. This link shows I. schoutedeni, which thus would be Mr. nolfi if I have well understood what you said, as the direct ancestor of Mr. praecursor, but it hasn't been wrote directly by a specialist it seems, and this is visibly obsolete for the rest of the lineage evolution which is no longer valid.

http://www.mineralienatlas.de/lexikon/index.php/Pal%E4ontologisches%20Portrait/Haie/Isurus

I have only one tooth from M. nolfi and little information in the end. I have found a publication from King et al 2013, that describes 2 teeth of M. nolfi from the Aktulagay section of West Kazakhstan, the upper side tooth has lateral cusplets, as the lateral teeth have too on the other documents that I had. What is strange for me is that the lateral teeth of C. schoutedeni, the first form, have less developed lateral cusps, which are stronger for M. nolfi specie, to disappear again with Mr. praecursor, or remain very weakly.

post-0-0-37653100-1401956660_thumb.png

My M. nolfi tooth from the London clay

post-0-0-43394100-1401956708_thumb.png

C. schoutedeni from The Cretaceous of the Congo

post-0-0-72836400-1401956784_thumb.png

Macrorhizodus nolfi - Aktulagay section W. Kazakhstan from King et al. 2013

post-0-0-42777400-1401956844_thumb.pngpost-0-0-20791400-1401956879_thumb.jpgpost-0-0-88705200-1401956903_thumb.png

Macrorhizodus nolfi

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Macrorhizodus praecursor

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Macrorhizodus praecursor with vestigial cusps

Selacien34,

Thanks for the information and figures. FF member non-remanie and I spent Sunday afternoon trading emails. He informed me of the presence of Macrorhizodus nolfi in the Ypresian of Kazakhstan and it is also figured in the book, "London Clay Fossil of Kent and Essex. It is a very rare species. I should have remembered M. nolfi. I can't believe I forgot about it.

Jess

Edited by Sélacien34
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